This is known as financial infidelity.
It's very common now that people do his and hers finances and are let loose to manage things on their own without a partner to be accountable to or to bounce ideas off and make joint decisions.
I suggest family pot for everything and regular budget meetings where both credit rating and reports are gone through together, under the guise of working to improve your credit ratings together.
Yes it's normally for gambling or general "cost of living", although in my opinion living beyond means, an Instagram life. Fancy new car on finance, clothes, lots of takeaways, holiday payments, very expensive food shop...
I think if men and women are married then the other spouse should have to sign off on any debt. It's so bad and so many sad stories of people decimating their spouses financial life (as they then often try and help) and their joint financial goals.
But that probably won't happen as debt is a big business and that would solve a lot of problems for people but not for debt companies profit. And then the tax the government gets.
I also think debt should be linked to income. It should be really low, like 10% your annual income maximum unsecured debt. I see people who are working in shop and have accrued close to 50k unsecured debt, it's crazy and it's very common.
But again that common sense approach would cost the debt companies profit and the government tax.
I suggest you both read the book total money makeover, start a joint budget allocating your income to categories in percentages and strip out everything you can from your budget, yes two cars for rural, are you driving about in new mid/upper range suv's or a little car each like a corsa? Unless your up a dirt track road, you don't need a 4x4 suv.
Try get him on the same page and talk to provider about cooling off period if possible to give loan back. Tell him he has committed financial infidelity and this is serious, what is he going to do to fix this between you both. And then you can consider your next move based upon his actions.
I'd be concerned he has more debt and want to log in together to view his credit rating and details held. Money-saving expert do a free app which is easy to understand. Just so you know what your dealing with.
If he resists I'd assume there is a lot more than 15k of debt.
Sorry youre in this position x